Engineering Questions with Answers - Multiple Choice Questions
Materials Science MCQ’s – Imperfection in Ceramics
1 - Question
In which of the following defect the density of the crystal is affected?
a) Schottky defect
b) Frenkel defect
c) Stone-Wales defect
d) Antisite defect
View Answer
Explanation: The density of the solid crystal in case of Schottky defect is less than the theoretical density of the material. This happens as the total number of ions in the lattice is less than the theoretical number of ions according to its volume, when this defect occurs.
2 - Question
Schottky and Frenkel defects are __________
a) interstitial and vacancy defects respectively
b) vacancy and interstitial defect respectively
c) interstitial defects
d) vacancy defects
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Explanation: Schottky defect occurs when oppositely charged ions leave the crystal and creating a vacancy and hence is a vacancy defect while in Frenkel defect an atom moves from it’s original site to an interstitial position and hence is an interstitial defect.
3 - Question
Frenkel defects change the ratio of cation to anions.
a) True
b) False
View Answer
Explanation: The above statement is false. Frenkel and Schottky’s defects do not change the ratio of cations and anions. The compound is stoichiometric.
4 - Question
In which of the following iron compounds, the compound is non-stoichiometric?
a) Fe2+ and Fe3+
b) Fe2+ ion only
c) Fe3+ ion only
d) It doesn’t depend on the iron ions
View Answer
Explanation: A compound is non- stoichiometric when there is presence of the same ion in two valence state in the compound. In this case that is Fe2+ and Fe3+.
5 - Question
In which of the following the concentration of defect is constant?
a) Point defect
b) Intrinsic defect
c) Extrinsic defect
d) Linear defect
View Answer
Explanation: The concentration of defect is constant in case of extrinsic defect. For example Rock salt structure like Nacl and MgO.
6 - Question
In which of the following the concentration of defect increases with temperature increase?
a) Point defect
b) Intrinsic defect
c) Extrinsic defect
d) Linear defect
View Answer
Explanation: The concentration of intrinsic defect increase with an increase in its temperature.
7 - Question
Which of the following does point defect does not depend on?
a) Density
b) Melting point
c) Hardness
d) Optical absorb
View Answer
Explanation: Point defects do not depend on the hardness of the material and it depends on density, optical absorb and the melting point of the material.
8 - Question
Transition metal oxides are highly defective.
a) True
b) False
View Answer
Explanation: The above statement is true. Transition metal oxides like NiO and FeO are often highly defective.